Project Summary Allogeneic hematopoietic stem cell transplantation (HSCT) is a long-established therapy for blood malignancies. The therapeutic benefit and potential cure achieved by HSCT is mediated by the graft-vs-tumor (GVT) effect that is derived from donor immune system. The overarching objective of the research projects in this Program Project application is thus to enhance this GVL effect for high risk patients for relapse by administering subsequent immunomodulation with the goal of developing novel strategies for selectively enhancing tumor immunity and improving patient outcomes. Specifically, Project 1 will focus on clinical trials for novel immunotherapies that are designed to enhance post-transplant immune reactivity pre-emptively using whole leukemia cell vaccination, neoantigen/minor histocompatibility antigens (mHAgs) vaccination or check point blockade inhibitor or to treat relapse using Treg depleted donor lymphocyte infusion plus check point blockade inhibitor. Project 2 will investigate the underlying mechanisms of GVL and the specific T cell responses to neoantigen/mHAgs vaccination generated in clinical trials carried out in Project 1. Project 3 will focus on the impact of clonal hematopoiesis (CHIP) in the donor stem cell product on clinical and immunologic outcomes after transplant. The primary objective of the Biostatistics and Data Management Core (Core 1) is to provide statistical collaboration for all investigators involved in this Program Project. This includes collaboration with project investigators in the design of clinical trials in Project 1 and laboratory studies in Projects 2 and 3, analysis of clinical and laboratory data and to establish correlations of clinical outcomes with laboratory results in Projects 1-3, and participate in manuscript writing in all Projects. Core 1 will also provide centralized mechanisms to assure the timely and complete capture of all clinical data in this Program Project. This includes collection and maintenance of necessary clinical information, data management support, quality control for clinical data, and oversight of clinical trial operations to ensure that all data elements required by each protocol are collected in timely fashion; and where necessary, design of research procedures and databases to allow blinded laboratory assessments and later integration with patient-level data for analysis. PHS 398/2590 (Rev. 11/07) Page Continuation Format Page